JPH1029531A - Electronically-controlled brake booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress adverse effects due to the time lag peculiar to the system of an electronically-controlled brake booster by controlling at least one control parameter in the system depending on the non-operating duration of braking pressure from the supply of drive signals to electromagnetic mechanisms to its rise in response to the drive signals. SOLUTION: An electronically-controlled brake booster comprises a housing part including vacuum chambers 23 and servo chambers 24 separated from the vacuum chamber 23 with movable walls 22 respectively, control valves 26 adapted to operate by electromagnetic mechanisms respectively, an ECU for generating drive signals 126 to operate the electromagnetic mechanisms, and a brake-pressure generator 2. The control valves 26 and the movable walls 22 are connected together respectively to relatively move to each other with respect to the housing. The brake-pressure generator 2 is connected to the movable walls 22 and generates brake pressure to brake the automobile depending on the positions of the movable walls 22. The drive signals I26 are produced by the ECU on the basis of control parameters which are controlled depending on the non-operating duration of braking pressure from the supply of the drive signals to the electromagnetic mechanisms 26 to the rise thereof in response to the drive signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled brake booster for a brake device used in an automobile brake system. The brake booster includes a housing having a vacuum chamber, a servo chamber separated from the vacuum chamber by a movable wall, and a control valve device operable by an electromagnetic mechanism. Are moved relative to each other with respect to the movable wall, the electromagnetic mechanism is connectable to an electronic controller that generates a drive signal to operate the electromagnetic controller, A brake pressure generator connected to move the wall, wherein the brake pressure generator generates a braking pressure for at least one brake of the vehicle in accordance with a position of the movable wall.

[0002]

[Prior Art] Similar system is DE (German patent) 4
0 28 290 C1. In this system, the operating speed of the brake pedal depressed by the driver at any position is the only criterion for extracting the automatic brake. In the system described herein, the operation speed of the brake pedal at any position depressed by the driver is compared with a fixed threshold value, and depending on the comparison result, whether the emergency brake is activated or not is determined. Is determined.

[0003] DE 41 02 496 A1 provides a pressurized system by measuring the brake pressure generated by a hydraulic brake circuit as the force applied to the brake pedal or as a value directly related thereto. Brake pressure is measured,
A brake pressure control device that locks a brake circuit when a threshold value is exceeded is disclosed.

In addition, in order to activate the emergency brake, the brake shaft output must be locked with respect to the main brake cylinder and the output pressure of the backup pressure source must be applied to the wheel brakes in a valve-controlled manner. As a result, the connection between the hydraulic side of the brake pedal and the wheel brake is no longer connected,
The brake pedal becomes "hard" and path-dependent control of automatic braking is no longer possible. There is no additional buffer amount corresponding to the driver depressing the pedal, and the main brake cylinder is fixed to the wheel brake.
This is the only possibility that the movement of the pedal can be simulated from variations in time. From the variation in the time, the amount of deceleration of the vehicle required by the driver is understood and considered in the future braking operation.

In addition, such operating methods include automatic braking operation that is not required by the driver, especially when starting the brake pedal mechanism, due to the system-specific delay time, the rigid hydraulic system, and the mechanical rebound of the brake booster and brake pedal mechanism. The operation speed of the brake pedal is generated such that the brake pedal is triggered. This occurs when the threshold is reached or exceeded for a short time. From the above, it can be seen that the predetermined threshold is reached too early for a less rigid brake system, and too late for a brake system that is too rigid. Since the stiffness of the brake system changes during the movement of the vehicle and during the useful life of the vehicle, reliable operation for the brake system is not always guaranteed.

[0006] DE 44 25 578 A1 proposes a method of activating a block protection brake system for motor vehicles which stabilizes the drive and / or prevents and controls slippage. This brake system
Regardless of the driver's intention, it has a pneumatically operated brake booster. Irrespective of the driver's intention, the brake booster is activated when the adjustment of the brakes starts, a quick filling of the vehicle wheel brakes is performed, and when the quick filling is finished, the ABS return pump increases the further pressure of the vehicle wheel brakes. Enhancement is achieved.

However, there is a disadvantage that the vacuum in the vacuum chamber is not quantitative during the brake adjustment process. The vacuum generated in the intake pipe can be used in the vacuum chamber.
o) Excessive vacuum variations can adversely affect system performance, especially in cars with engines. For example, an improper vacuum results in a slow response. A further proposal in DE 44 25 578 A1 is that once the brake adjustment has begun, the pressure additive stored in the pressure accumulator is used for rapid filling of the wheel brakes. .

On the other hand, as a result of the above arrangement, the brake adjustment process is independent of the vacuum in the vacuum chamber. However, a disadvantage arises in that labor and cost are required due to necessary additional elements such as a pressure accumulator, a shutoff valve, and a pressure sensing means.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronically controlled brake booster for a motor vehicle brake system of the above kind, which can reduce the adverse effects of the system-specific delay time.

[0010]

In order to solve this problem, the drive signal is generated by the electronic control unit ECU independently of at least one control parameter, and the at least one control parameter is generated by the electromagnetic control unit. An adjustment is made in accordance with the inactive time of the brake pressure from when the drive signal is supplied to the expression mechanism until the brake pressure increases in response to the signal.

The present invention is based on the following surprising findings. The dead time of the system can be used as a factor for the operation of the brake booster. The performance of the brake system controller improves with the pressure in the vacuum chamber. This pressure can be detected by measuring the time interval, ie, the dead time. The present invention is applied to an electronically controlled brake system for an automobile. The system includes a brake pressure generator that is activated via a brake pedal to adjust the brake pressure of at least one wheel brake. The electronically controlled brake booster is provided to assist in activating the generation of the brake pressure or to automatically activate the generation of the brake pressure independently of the activation of the brake pedal. The present invention can improve the performance of an electronically controlled braking system of the type described above, while avoiding the above disadvantages.

[0012] Indirectly, the brake pressure of one or more wheel brakes is adjusted according to the vacuum rate of the vacuum chamber of the electronically controlled brake booster.

The electronically controlled brake booster according to the present invention includes a sensor for sensing an operation state of the vehicle brake system for the electronic control unit ECU and generating a signal characterizing the operation state. These signals are quantified by the control device that creates the drive signals.

This sensor is formed as a pressure sensor that senses at least the brake pressure.

In one embodiment of the present invention, the electronic control unit comprises:
Controller means having a reference variable input port and a drive signal output port is provided. The control parameter is PID
It characterizes the controller means of operation. The amplification coefficient is K, the integration time constant is T _I , and the differentiation time constant is T _D. Therefore, the drive signal can be expressed as follows.

[0016]

(Equation 3)

Alternatively, the electronic control unit may include a process computer (microcomputer) having an input port for a reference variable and an output port for the drive signal. The control parameters characterize the recursive control algorithm executed on the process computer based on the equations shown below.

[0018]

(Equation 4)

Where the sample time is T ₀ ; p ₁ = 1; q
_{0 = K (1 + T D} / T 0), q 1 = -K (1 + 2T D /
T ₀ −T ₀ / T ₁ ); and q ₂ = K T _D / T ₀ .

[0020] In an alternative embodiment of the recursive algorithm, the control parameters are repeatedly adjusted during the inactive time in response to the current duration of the inactive time. In this embodiment, the parameters of the situation are continuously updated while the dead time is increasing. As a result, as soon as the downtime ends,
The parameters are available in optimal settings. Thus, the controller can operate more quickly.

Therefore, the PID operation of the controller means is mounted on the adaptive means for adjusting the control parameter, and the movement of the PID operation of the controller means is adapted to the variable characteristics of the brake pressure device.

According to the present invention, the electronic control unit is adjusted to perform the following steps. - the step of detecting the change by monitoring the reference variable (Pnominal), - continuously, - determining if the dead time T _t has ended, - in response to a predetermined relationship dead time T _t Setting the parameters p ₁ , q ₀ , q ₁ , q ₂ as a function of the current value of, and determining if the brake pressure (p ₂₉ ;) has changed.

The electronic control unit is configured to determine whether the maximum value of the dead time T _t has been exceeded by detecting a change in the reference variable (Pnominal) by starting a timer. This device allows for security checks during operation and simplifies system design.

The electronic control unit (ECU) determines the non-operation time T
_The control parameters K, T _I ,
It is also possible to configure to set T _D , p ₁ , q ₀ , q ₁ , q ₂ . Therefore, during operation, it is necessary to execute a smaller program in a shorter time.

Adjusting the brake pressure is particularly advantageous in a closed control loop. The application controller optimizes the control operation to compensate for harmful pressure fluctuations in the vacuum chamber of the electronically controlled brake booster.

Other benefits can be achieved using an adaptive controller. Since the adaptation algorithm of the adaptation controller does not need to measure system parameters, it is advantageous in terms of cost because measurement means such as a pressure sensor for sensing the pressure in the vacuum chamber can be saved.

[0027] Other features, advantages and features of the present invention will become apparent from the following description, taken in conjunction with the drawings.

[0028]

FIG. 1 shows an electronically controlled brake system for a motor vehicle. The brake pedal 1 activates a brake pressure generator 2 via an operating element. The brake pressure generating device 2 includes a brake cylinder 25 and a piston 28 that defines a servo chamber 29. The servo chamber 29 is supplied with brake fluid from the storage unit 27. The brake pipe (line) 3 connects the wheel brake 4 of the automobile and the servo chamber 29.

The valve component 5 is disposed in the middle of the brake pipe 3 between the brake pressure generator 2 and the wheel brake 4. The valve configuration unit 5 is an electronic control unit ECU
Two solenoid valves 5a, 5
b and serves to regulate the pressure of the wheel brake 4. For this purpose, the electronic control unit ECU determines the rotational operation of the wheels arranged in connection with the wheel brakes 4, and controls the solenoid valves 5a, 5b to increase, decrease, and maintain the pressure. Set the state.

In the electronically non-operating state, the first solenoid valve 5a is in the open state and the second solenoid valve 5b is in the closed state, so that the pressure of the wheel brake 4 can be formed.
When only the first solenoid valve 5a is activated, the first solenoid valve 5a is closed, and the second solenoid valve 5a is closed.
b is maintained in a closed state so that the pressure of the wheel brake 4 becomes constant. First and second solenoid valves 5a
When both 5b and 5b are in the operating state, the first solenoid valve 5a is closed and the second solenoid valve is opened. In this case, the brake fluid is supplied from the wheel brake 4 to the intermediate fluid storage 6 through the second solenoid valve 5b.
Flows to The brake fluid in the intermediate storage 6 is returned to the brake pipe 3 by the hydraulic pump 7. The hydraulic pump 7 is driven by an electronic motor 8 controlled by an electronic control unit ECU. The valve component 5 can be formed by a flow control valve instead of the first solenoid valve 5a, or by an electromagnetically activated 3/2 type (3/2 way) valve instead of the two solenoid valves 5a and 5b. It can also be formed.

The brake pressure generator 2 has a pneumatic brake booster 21 for amplifying the operating force generated through the brake pedal 1. The movable wall 22 partitions the outer periphery of the pneumatic brake booster 21 into a vacuum chamber 23 and a servo chamber 24. Vacuum chamber 2 to create a vacuum
3 is connected to a vacuum source Vac (not shown).

In an automobile equipped with an Otto engine, a vacuum generated by an intake pipe is generated by a vacuum source V
Available as ac. However, in automobiles driven by diesel engines and electric motors, an additional vacuum pump is required as the vacuum source Vac. Brake pedal 1
Is activated, the brake booster 21 operates in a known manner, and the servo chamber 24 is brought to the atmospheric pressure so that the pressure difference acts on the movable wall 22. This pressure difference is the brake pedal 1
Assists the actuation force generated via. Under the non-operating state, the vacuum chamber 23 and the servo chamber 24 are connected to each other and compensate for each other, so that the pressure difference does not act on the movable wall 22.

The brake booster 21 can be electronically controlled via an electromagnetic mechanism 26. The electromagnetic mechanism 26 operates a control valve (not shown) so that the brake booster 21
To three different control positions (I, II, III). -In the first so-called "strengthening position" (I), the connection between the vacuum chamber 23 and the servo chamber 24 is cut off, the connection between the servo chamber 24 and the atmosphere is made, and the pressure difference at the movable wall 22 is strengthened or increased. In the second so-called “holding position” (II), the connection between the vacuum chamber 23 and the servo chamber 24 and the connection between the servo chamber and the atmosphere are interrupted, and the pressure difference acting on the movable wall 22 is maintained. In a third so-called "relief position" (III), the vacuum chamber 23
The connection between the servo chamber 24 and the atmosphere is cut off, and the pressure difference acting on the movable wall 22 is eliminated by the pressure compensation operation.

The control valve is moved to various control positions (I, II, II
In order to move to I), the electronic control unit ECU supplies a drive signal current I ₂₆ to the electromagnetic mechanism 26, and the drive signal current I ₂₆
The control position can be set by varying ₂₆ , for example, by pulse width modulation. A brake pressure p ₂₉ generated in the servo chamber 29 of the brake cylinder 25 and supplied to the brake pipe 3 is sensed by a sensor 31, a sensing signal is transmitted to the electronic control unit ECU, and a solenoid current I that drives the electromagnetic mechanism 26 is controlled. ₂₆ to adjust the braking pressure p ₂₉ as a function of the desired pressure value and / or pressure characteristics Pnominal by varied.

By electronically controlling the brake booster 21, the brake operation can be executed automatically or independently of the operation of the brake pedal 1. This is, for example,
Used to perform anti-slip control or drive dynamics control or distance control. The sensor 11 is provided with a parameter related to the operation of the brake pedal 1 (pedal movement) in order to perform a numerical operation in the electronic control unit ECU so that the brake operation is executed even in an emergency condition, for example, when a certain reference pedal operation speed is exceeded. , Pedal force, pedal operation speed).

In the electronically controlled brake system shown in FIG. 1, a switching valve 51 is disposed on the brake pipe 3 and is driven by an electronic control unit ECU. The switching valve 51 connects the brake pressure generator 2 to the wheel brake 4
Alternatively, it acts to connect to the suction side 7e of the pump 7. For this purpose, when the electronic control is inactive,
While the switching valve 51 is disconnected from the suction side 7e of the pump 7, the brake pressure sensor 31
The switching valve 51 is designed to be connected to the switching valve 51. When the switching valve 51 is driven, the brake pressure generator 2 is connected to the suction side 7e of the pump 7 while the connection with the wheel brake 4 is cut off. The embodiment of the switching valve 51 as a 2/3 type valve can be replaced in a known manner by two 2/2 type valves as shown in FIG. The pressure limiting valve 52 is connected in parallel with the switching valve 51 and, when a predetermined pressure value at the output 7a of the wheel brake 4 or the pump 7 is exceeded, the wheel brake 4 or the pump 7
Is connected between the output side 7a and the brake pressure generator 2. The check valve 53 is located between the intermediate storage 6 and the suction side 7 e of the pump 7, so that only a flow connection from the intermediate storage 6 to the suction side 7 e of the pump 7 is possible.

Drive control, which improves the stability of the vehicle, especially during cornering, by means of automatic braking or anti-slip control, requires a very rapid pressure build-up of the wheel brakes 4. To this end, when the brake adjustment process starts, the pump 7 is started by activating the electric motor. The switching valve 51 is actuated and the brake pressure generator 2 is connected to the suction side 7e of the pump 7;
And the connection of the wheel brake 4 is closed. The brake booster 21 is controlled independently of the operation of the brake pedal 1;

As a result, a quick filling by the pump 7 via its suction side 7e is performed so that the appropriate pressure level is available at the output side 7a of the pump 7 already during the start-up state. The pressure p adjusted in the servo chamber 29 of the brake pressure generator 2 by controlling the brake booster 21
₂₉ is 5 to 30 bar (b) depending on the condition of the road surface
ar). After the pump 7 is started, the control of the brake booster 21 is completely or partially canceled, and the pressure adjustment of the wheel brake 4 is performed by controlling the valve component 5. The operation of the switching valve 51 is canceled only after the brake adjustment process is completed.

FIG. 2 shows a closed control loop in which the brake pressure generator 2 is controlled. The output amount, that is, the adjustment amount is the brake pressure p ₂₉ generated in the servo chamber 29. The input amount to the controller member is an electromagnetic variable 26 which is an operation variable.
A vacuum rate p ₂₃ of the vacuum chamber 23 is exogenous variables and the solenoid current I ₂₆ which drives the. The controller means is preferably integrated with the electronic control unit ECU. Further, the controller means subtracts the control amount p ₂₉ from the reference variable Pnominal to obtain the control difference x _d which is the input amount of the controller R.
Are provided. The output of the controller R is an operation variable I _26. The controller R can be designed to be optimal for the parameters and the structure. Controllers that are optimal for the parameters are mainly conventional controllers, which perform proportional and / or integral and / or derivative operations. This conventional controller is realized by incorporating a program in the form of an electronic circuit or a process computer. Optimal controllers, which are mainly programmed in the process computer, include, for example, speed indicators, which are particularly suitable for adaptive brake adjustment.

The realization of the controller means is particularly useful in the processing computer of the electronic control unit ECU. If the controller R is designed as a PID controller, it can be programmed as a recursive algorithm with relatively low effort. Based on the idealization equation of the analog PID controller, using the amplification factor K, the integration time constant T _I and the differentiation time constant T _D , the manipulated variable I ₂₆ which is the output amount of the controller R is
As is well known, it can be expressed as follows.

[0041]

(Equation 5)

The recursive brake adjustment algorithm R is as follows by separation.

[0043]

(Equation 6)

Assuming that the inactive time is T0, the analog PI
The following relationship occurs between the parameters of the D controller and the recursive brake adjustment algorithm R:

[0045]

(Equation 7)

Based on the above relationship, the parameters K, T
_I, known adjustment rules analog controllers T _D can be used in principle, to adjust the parameters _{p 1, q 0, q 1} , q 2.

Further, the controller R carries an adaptive algorithm A. This algorithm A adapts the operation of the controlled recursive brake adjustment algorithm R (control member) to the variable characteristics of the brake pressure generator 2 by changing the parameters p ₁ , q ₀ , q ₁ , q ₂ . .
This is to improve the braking adjustment level and thereby contribute to the capacity of the system. The change in the characteristics of the brake pressure generating device 2 (control member) under the control is mainly caused by the fluctuation of the unpredictable vacuum rate p ₂₃ (external variable) which mainly occurs in an automobile having an Otto engine. Is caused.

As the adaptive algorithm A, an algorithm having "feedback (closed loop adaptation)" is used, and the variable characteristic of the brake pressure generator 2 (control member) is indirectly determined, for example, identification of brake adjustment level or continuous determination. To sense. For this purpose, the adaptation algorithm A, and the reference variable Pnominal, and the controlled variable p _29, inputs the operation variables I _26.

Alternatively, a "controlled" adaptation algorithm A (open loop adaptation) can be used. However, this requires the measurement of exogenous variables p _23. This measurement, additional pressure sensors and digitizing means corresponding thereto for sensing the vacuum rate p ₂₃ of the vacuum chamber 23 is required, as a result, again, the system is so costly becomes complicated.

The change in the characteristics of the brake pressure generator 2 (control member) under control depends on the variation in the vacuum rate p ₂₃ (external variable). The change in this characteristic will be described below with reference to the characteristic of the closed-loop control shown in FIGS. 3A and 3B. 3a and 3b show the brake pressure p ₂₉ (control variable) as a function of time. The brake pressure is the following cases, obtained in ideal vacuum rate p ₂₃ of about 0.8 bar according to FIG. 3a (bar), according to Figure 3b about 0.2 bar (ba
obtained by vacuum rate p ₂₃ of r). The case where the reference variable Pnominal is increased from 0 bar to a value of about 10 bar in one step; and the case where the controller R which operates according to the PID algorithm without using the adaptive algorithm A carried on the controller R is used. , Parameters p ₁ , q ₀ , q ₁ , q
₂ is a case that has been determined to be optimal to the ideal vacuum rate p ₂₃ of about 0.8 bar.

Since the parameters p ₁ , q ₀ , q ₁ , q ₂ have been determined to be optimal for an ideal vacuum rate p ₂₃ of about 0.8 bar, the brake pressure p ₂₉ as a function of time shown in FIG. Is adjusted very quickly. This time function is mainly characterized by a small time constant T _g of about 20 ms. However, since the vacuum rate p ₂₃ is about 0.2 bar, as will be understood from the brake pressure p ₂₉ as shown in Figure 3b as a function of time, the adjustment operation is deteriorated remarkably. Time constants The T _g characterizes the adjustment operation is increased to a value of about 500 ms. Such a delay in the adjustment operation degrades the performance of the system. This is particularly disadvantageous in the operating dynamics control the brake pressure p ₂₉ needs to be increased as quickly as possible.

As a countermeasure, an adaptive algorithm A is mounted on the controller R. Vacuum rate p of about 0.2 bar
In _23, if the reference variable Pnominal is increased in one step from 0 to about 10 bar, the brake pressure p ₂₉ is a time function shown in Figure 3c. The use of the adaptive algorithm A significantly improves the braking operation compared to FIG. 3b, so that the time constant T _g is about 30 ms. This improvement is based on the fact that the adaptive algorithm A mainly increases the controller gain K by changing the parameters p ₁ , q ₀ , q ₁ , q ₂ of the adjustment algorithm R.

As can be seen from FIGS. 3a to 3c, each of the curves of the brake pressure p ₂₉ as a function of time represents a dead time T _{t at} which the delay of the brake pressure p ₂₉ is further increased.
Contains. Vacuum rate p ₂₃ of about 0.8 bar (FIG. 3a)
In this case, the dead time T _t is about 40 ms, and at a vacuum rate p _{23 of} about 0.2 bar (FIGS. 3b and 3c), the dead time T _t is about 100 ms.

Using the known dead time T _t , a conclusion can be drawn regarding the value of the pressure p _{23 in} the vacuum chamber 23. This relationship can be beneficially applied to the adaptive algorithm A, which is shown in the form of the flow chart of FIG. As a result, in the first step 110, for example, the reference variable Pnominal
Is in a standby state for the control operation as can be understood from the change of the control operation. In the second step 120, after determining the start of the control operation, the control variable p ₂₉ is monitored, and continuously: in the programming step 121, the dead time T _t is determined. Setting the parameters p ₁ , q ₀ , q ₁ , q ₂ as a function of the dead time T _t according to a predetermined relationship. - In program step 123, waits for a control quantity p ₂₉ from changing. - In the third step 130, after determining the beginning of the change in the controlled variable p _29, p ₁ of the brake adjustment algorithm R,
The parameters of q ₀ , q ₁ , q ₂ are programmed in step 122
Set as previously determined with. -In a fourth step 140, for example, the reference variable Pnominal
Wait for the end of the control operation, such as resetting. - In a fifth step 150, the control operation is completed, the parameters _{p 1, q 0, q 1} , q 2 is initialized, the program continuing to step 110.

The adaptive algorithm A can be programmed in the process computer of the electronic control unit ECU with little effort, and there is no need to increase the capacity of the process computer, so that no extra cost is required. In comparison, an adaptive algorithm that identifies a control member based on the manipulated variable I ₂₆ and the control amount p ₂₉ by digitizing the parameter by a mathematical model so as to change the controller parameter as a function of the expected element parameter requires a considerable amount of time. This requires programming effort and requires more computer capacity.

Non-operation time T _{t in} program step 121
Can be determined by a timer function available on the process computer. Therefore, for example, the first step 1
After the start of the control operation is determined in step 10, the non-operation time T
_The monitoring timer or free running timer can be reset and restarted so that the current timer value is read continuously in program step 121 to determine _t .

Program step 12 of adaptive algorithm A
In 2, the parameters p ₁ , q ₀ , q ₁ , q ₂ are set as a function of the dead time. Parameters p ₁ , q ₀ ,
If there is a proportional relationship between q ₁ , q ₂ and the dead time T _t , this setting becomes feasible by simply solving a simple equation. The characteristic sequence table can also be stored in the memory of the process computer. This table contains the parameters p ₁ , q
_0, q _1, q ₂ and a predetermined relationship between the dead time T _t is shown. In another dimension of such a characteristic array, the behavior of the reference variable Pnominal is also shown simply. Reference variable P
Since the value of the nominal process change is measured by the dynamic characteristic value expected during the control operation, the parameters p ₁ , q ₀ , q ₁ , q ₂ can be avoided by adjusting, and a higher braking effect is achieved.

It is extremely simple to change the amplification factor K by discretely adjusting the parameters p ₁ , q ₀ , q ₁ , and q ₂ . In the program step 122, a value in a certain range is assigned to the inactive time _Tt determined in the program step 121, and a certain amplification coefficient K is designated as a value in the range. For example, three discrete ranges of values are determined for dead time T _t, resulting in Assignment Table 1 below.

[0059]

[Table 1]

For a short dead time T _t measured at high vacuum pressure p ₂₃ , a long dead time T _t measured at low vacuum pressure p _23
An amplification factor smaller than the case of _t is set.

By the initialization in the program step 150,
The parameter p ₁ at an ideal vacuum rate p ₂₃ of about 0.8 bar,
q ₀ , q ₁ and q ₂ are optimally set. As described above, the parameters p ₁ , q ₀ ,
When setting q ₁ and q ₂ , this setting means that the minimum amplification factor K ₁ is obtained at the time of initialization. As a result, the short dead time T _t is measured at a high (ideal) vacuum pressure p ₂₃ .

As can be seen in the flow chart of FIG. 4, another optimal programming step 210 is provided between each of the first and fourth steps 110, 140 and the second step 120 or the programming step 123. . Program step 21
0 operates to determine the time of the control operation, and aborts the control operation when a given time limit is exceeded. This behavior is
The higher-order system requests a reset of the reference variable Pnominal, executes this reset directly, and continues from the fifth step 150 with the parameters p ₁ , q ₀ , q ₁ , q
_This is performed, for example, in program step 200 by initializing ₂ and waiting for the start of a new control operation. The determination of the duration of the control operation can be performed in the same manner as the determination of the dead time _Tt in the program step 121 by using the timer function available on the process computer. In order to monitor the determination of the dead time T _t and to terminate the control operation if a certain time limit is exceeded, another optimal program step 201 continuing from the program step 200 is arranged between the program steps 122 and 123. I have.

Time related programming steps 210 and 20
1 contributes to a higher security of the system. This, in part, is because the control operation only a predetermined time interval so as to avoid the braking pressure p ₂₉ is increased dangerously becomes possible, on the other hand, it or beyond the given time period If it does, a conclusion is drawn about the system error and the system is monitored for a specific dead time _Tt so that the corresponding correction program can be executed.

[0064]

According to the present invention, it is possible to provide an improved electronically controlled brake booster capable of suppressing an adverse effect due to a system-specific delay time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an electronically controlled braking system of a motor vehicle.

FIG. 2 is a diagram showing a closed control loop for operating an electronically controlled brake system of an automobile.

3a, 3b and 3c show three different control features of a closed control loop for operating an electronically controlled braking system of a motor vehicle, respectively.

FIG. 4 is a flowchart of an adaptive algorithm for optimizing a control operation of an electronically controlled brake system of a vehicle.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 brake pedal 2 brake pressure generator 3 brake pipe 4 wheel brake 5 valve component 11, 31 sensor 21 brake booster 22 movable wall 23 vacuum chamber 24 servo chamber 25 brake cylinder 26 electromagnetic mechanism 28 piston 29 servo room ECU electronic control unit I ₂₆ drive signal (current) P ₂₆ brake pressure T _t non-operation time K, T _I , T _D , p ₁ , q ₀ , q ₁ , q ₂ Control parameters

Claims (11)

[Claims] An electronically controlled brake booster for a vehicle brake system, comprising: a vacuum chamber (23); said vacuum chamber (23) and a movable wall (2).
A housing section including a servo chamber (24) separated in 2); and an electromagnetic mechanism (26), which operates by the movable wall (22).
A control valve unit, which is moved relative to the housing with the movable wall (22);
The electromagnetic mechanism (26) is connected to an electronic control unit (ECU), and the electronic control unit (ECU) generates a drive signal (I ₂₆ ) for driving the electromagnetic mechanism (26). And further operably connected to the movable wall (22), wherein at least one of the vehicles is responsive to a position of the movable wall (22).
A brake pressure generator (2) for generating a brake pressure for the two brakes, wherein the drive signal (I ₂₆ ) includes at least one control parameter (K, T _I , T _D ; p ₁ , q ₀ , q ₁₎ , Q ₂ ) generated by the electronic control unit (ECU), and the at least one control parameter (K, T _I ,
T _D ; p ₁ , q ₀ , q ₁ , q ₂ ) during the period from when the drive signal (I ₂₆ ) is supplied to the electromagnetic mechanism (26) until the brake pressure increases in response thereto. An electronically controlled brake booster, which is adjusted in accordance with the brake pressure non-operation time (T _t ). 2. The electronic control unit (ECU) includes a sensor (31) for sensing an operating condition of a vehicle brake system and generating a signal characterizing the operating condition, wherein the signal generates the drive signal. 2. The electronically controlled brake booster for a vehicle brake system according to claim 1, wherein the electronically controlled brake booster is digitized by a device (ECU). 3. The electronically controlled brake according to claim 2, wherein the sensor (31) comprises at least a pressure sensor for sensing the brake pressure (p ₂₉ ). booster. 4. The electronic control unit (ECU) includes an input port for a reference variable (Pnominal) and the drive signal (I ₂₆ ).
Controller means (A, R) having the following output ports, and the control parameters (K, T _I , T _D ) are PI
It has the characteristics of the controller means (A, R) for executing the D operation, and has an amplification factor K, an integration time constant T _I , and a differentiation time constant T _D
As a result, the driving signal (I ₂₆ ) becomes 3. An electronically controlled brake booster for a vehicle brake system according to claim 2, wherein: 5. The electronic control unit (ECU) includes an input port for a reference variable (Pnominal) and the drive signal (I ₂₆ ).
A process computer (microprocessor) having an output port for the control parameters (p ₁ ,
q ₀ , q ₁ , q ₂ ) are the sampling times T ₀ , p ₁
= 1; q ₀ = K (1 + T _D / T ₀ ), q ₁ = −K (1+
2T _D / T ₀ -T ₀ / T ₁ ); and q ₂ = K T _D /
The following equation that is T ₀ 5. An electronically controlled brake booster for a vehicle brake system according to claim 1, characterized in that it is a feature of a recursive control algorithm executed on a process computer on the basis of: 6. The control parameter (p ₁ , q ₀ ,
5. The device according to claim 1, wherein q ₁ , q ₂ ) is adjusted according to a non-operation time (T _t ) when the sensor (31) detects an increase in the brake pressure. Electronically controlled brake booster for an automotive brake system according to claim 1. 7. The control parameters (p ₁ , q ₀ ,
q ₁ , q ₂ ) is adjusted repeatedly during the elapse of the inactive time according to the current duration of the inactive time (T _t ). Electronically controlled brake booster for an automotive brake system according to claim 1. 8. The PID operation of the controller means includes an adaptive means (A) for adjusting the control parameters (p ₁ , q ₀ , q ₁ , q ₂ ), and the PID operation of the controller means Electronically controlled brake booster for a vehicle brake system according to any one of claims 1 to 7, wherein the movement of the brake pressure generator (2) is adapted to various characteristics of the brake pressure generator (2). 9. The electronic control unit (ECU) monitors a reference variable (Pnominal) to detect a change in the reference variable (Pnominal); and continuously determines whether or not the dead time _Tt has expired. Setting the parameters p ₁ , q ₀ , q ₁ , q ₂ as a function of the current value of the dead time T _t according to a predetermined relationship; and determining whether the brake pressure (p ₂₉ ;) has changed. 9. The electronically controlled brake booster for a vehicle brake system according to claim 1, wherein the electronically controlled brake booster is adapted to perform the determining step. 10. The electronic control unit (ECU) is adapted to, upon detecting a change in a reference variable (Pnominal), activate a monitoring timer to determine whether the maximum value of the dead time _Tt has been exceeded. An electronically controlled brake booster for a vehicle brake system according to any one of the preceding claims. 11. The electronic control unit (ECU) controls the control parameters K, T _I , T _D , p ₁ , q ₀ , q ₁ , and q ₂ according to a predetermined time interval of the non-operation time T _t. 8. An electronically controlled brake booster for an automotive brake system according to claim 1, wherein the booster is adapted to set.